Abstract: The invention relates to a method for generating for at least one macroblock of a high resolution image at least one motion predictor from motion data associated to macroblock(s) of a low resolution image.

Abstract: A method for modifying a reference block of a reference image, the method includes transforming the reference block into a first set of coefficients, modifying the first set of coefficients by help of one or more weights and inverse transforming the modified first set of coefficients wherein the weights are determined by help of one or more further pixels of the current image and by help of one or more further reference pixels of the reference image.

Abstract: A method for coding a current block of a sequence of images is disclosed. The method comprises: determining at least one candidate motion vector associated with a neighbouring block of said current block, determining a prediction motion vector from the candidate motion vector, and coding the current block from the prediction motion vector. Advantageously, the prediction motion vector is determined according to the following steps: determining, for the candidate motion vector, a corrective motion vector so as to minimise a distortion calculated between the neighbouring block successively coded and reconstructed and a prediction block motion compensated by the at least one candidate motion vector modified by the corrective motion vector, and determining the prediction motion vector from the candidate motion vector modified by the corrective motion vector.

Abstract: The invention relates to a method for reconstructing a picture that is part of a sequence of pictures, from coded digital data, representative of said current picture. It comprises the following steps: construct, for each picture block, first and second prediction blocks (from a first picture and a second picture previously reconstructed, and calculate, for each block, a confidence value representative of the proximity between the visual content of the first predictive block and the visual content of the second predictive block, and reconstruct each block from a part of said coded digital data representative of said block and initial auxiliary data calculated from the first and second predictive blocks when the block confidence value is greater than a predetermined threshold.

Abstract: The invention relates to spatially scalable encoding and decoding processes using a method for deriving coding information. More particularly, it relates to a method for deriving coding information for high resolution pictures from the coding information of low resolution pictures. The method mainly comprises the following steps: Computing geometrical parameters characterizing the position of said high layer macroblock relatively to the corresponding base layer macroblocks and deriving from these parameters a macroblock class; Deriving a partition and possibly sub-partitions for each partition of said high layer macroblock from corresponding base layer macroblocks partition and sub-partitions on the basis of the geometrical parameters and HL MB class; and Deriving motion information for said high layer macroblock from motion information of corresponding base layer macroblocks.

Abstract: A method for decoding a stream of coded data to reconstruct a current block of a sequence of images is disclosed. The method comprises the steps of: reconstructing for the current block a first item of motion data from a stream of coded data, identifying a first prediction block with the first item of motion data, determining a second item of motion data by template matching, identifying a second prediction block with the second item of motion data, reconstructing the current block from the first and second prediction blocks. The step of determination of the second item of motion data is a function of the first distortion calculated between the first prediction block and the second prediction block.

Abstract: The picture and coding method comprises the following steps: coding of the lowest resolution picture to provide coded data for a base layer of the coded data flow, zoom of the picture to obtain a low resolution zoomed picture of dimensions of those of the picture for the common video part, coding of to supply coded data to an upper layer of the coded data flow and using at least one of the following modes: predictive inter layer coding using a previous low resolution zoomed picture in which a predicted block and a motion vector defining this block is determined, predictive inter layer coding using a current low resolution zoomed picture in which a predicted block and a motion vector defining this block is determined.

Abstract: A method for coding a current block of an image is disclosed that comprises: determining, for the current block, current coding parameters, determining, for at least one neighbouring block of the current block previously coded and reconstructed, a neighbouring residual block from current coding parameters, and coding the current block with the current coding parameters according to the neighbouring residual block.

Abstract: The process comprising splitting of an image into blocks, intra coding of a current block using spatial prediction based on a matching pursuit algorithm selecting, from a dictionary of atoms, the atom the most correlated with a causal neighborhood of the current block, is characterized in that it performs the following steps: determination of the two dimensional shift between the causal neighborhood and the selected atom, generation of at least, a new phased atom taking into account the values of the two dimensional spatial shift, use of this new atom for intra prediction, according to the matching pursuit algorithm, if better correlated than the selected one. Application to video data compression.

Abstract: A method for coding an image divided into sub-regions is described. The coding method comprises the following steps: extracting from the image sub-regions representative of other sub-regions of the image, coding the sub-regions representative of other sub-regions at a first quality, and coding the other sub-regions at a second quality strictly lower than the first quality.

Abstract: Methods for determining for high layer macroblocks that use inter-layer prediction, a partitioning of the macroblock. The methods include dividing the high layer macroblock in non-overlapping high layer blocks of a predefined size; determining a corresponding base layer pixel for one pixel, called reference pixel, of each high layer block; identifying, for each reference pixel, a base layer macroblock to which the corresponding base layer pixel belongs, a base layer partition to which the corresponding base layer pixel belongs in the identified base layer macroblock, a base layer sub-partition to which the corresponding base layer pixel belongs in the identified base layer partition if the sub-partition exists; deriving, for each of the high layer block, a single value, called Partlnfo value; and determining a partitioning of the high layer macroblock in macroblock partitions by comparing between them the Partlnfo values associated with each of the high layer blocks.

Abstract: A method for arithmetic coding of symbols in a stream is described. The method comprises the following steps: coding a current symbol with a current probability model, and updating the current probability model according to the coding of the current symbol. selecting the current probability model in a set of at least two probability models according to a coding cost criterion, and coding an identifier of the selected probability model.

Abstract: A method for video coding of at least one digital picture sequence is disclosed. The pictures of said sequence can be intermediary pictures or key pictures used as references for the coding by motion compensation of intermediary pictures. The intermediary pictures are coded per area based on a global motion compensation GMC in the forward and backward direction from key pictures, the areas of the intermediary picture being constituted either by merging of global motion compensated key picture areas, or by conventional coding, the choice between merging and conventional coding being made according to the result of a measurement of coherency between the signals of global motion compensated key picture areas. A video coding device and a video decoding device are also disclosed.

Abstract: A method for decoding a stream of coded data representative of a sequence of images is disclosed. The decoding method comprises determining a prediction block, calculating the average of said prediction block, reconstructing, from said stream, a DC coefficient and AC coefficients relating to said current block, calculating an average of said current block from said average of said prediction block and said DC coefficient, calculating a weighted prediction parameter as being the ratio of the average of said current block and the average of said prediction block, transforming a block of coefficients comprising a null value as DC coefficient and said reconstructed AC coefficients into a residual block, reconstructing the current block by merging said residual block and said prediction block weighted by said weighted prediction parameter. A method for coding is further disclosed.

Abstract: The method realizes a motion compensated temporal filtering (MCTF), the temporal filtering being replaced by an intra mode coding to obtain at least one low (L) or high (H) frequency picture if the current picture has a level of correlation with a lower previous picture at a threshold, the low frequency pictures obtained (L) being thus scaled to be adapted, at the energy level, to the pictures obtained by motion compensated temporal filtering, and comprises, at the end of analysis: a selection of the pictures obtained by intra coding of a picture of a low decomposition level with the additional condition, for the high frequency pictures, that this picture is derived itself from an intra coding. a calibration of the picture selected by carrying out at least one reverse step of the scaling step. The applications relate to video compression with temporal prediction.

Abstract: A method for predicting a current block belonging to a current image with a view to the coding or the reconstruction of the current block is described. The method comprises the following steps: a) determining for the current block a reference block from at least one motion data previously associated with the current block, b) verifying if a predefined condition is fulfilled, the condition being representative of a temporal variation between the image data of the reference block and the image data of a prediction block of the reference block previously determined from at least one motion data associated with the reference block, c) modifying the motion data according to the result of the verification and d) generating a final prediction block for the current block from the motion data of the current block.

Abstract: Fully scalable encoder and decoder for interlaced video. A method for encoding an interlaced sequence of digital video data decomposes the interlaced video sequence into first and second fields, performs digital filtering to get lower frequency and higher frequency component signals of the first fields, and uses spatio-temporal filtering and motion estimation for generating base layer signals being suitable for reconstruction of a progressive mode video sequence in a receiver. Advantageously, both the spatio-temporal filter at the encoder, and the inverse process at the receiver, can perform scaling in spatial and temporal dimension. The second fields are used to generate enhancement signals, which enable a receiver to reproduce an interlaced video sequence of the full, or scaled, spatial and/or temporal resolution.

Abstract: In video encoding, the video frames are spatio-temporally filtered for reduction of spatial and temporal redundancy before they are entropy encoded. Known filtering schemes consider temporally successive frames and are static. It is probable but not necessary that successive frames are most efficient to encode. Therefore, a plurality or all possible frame order permutations are considered for a group of frames (GOP) and evaluated based on a global criterion, which is the sum of local criterion values computed over successive subsets of permuted frames. The local criterion value is deduced from motion estimation processed on each considered set of frames. The best ordering is chosen as the one that minimizes the global criterion value.

Abstract: Often hierarchical bi-directionally predicted frame structures are used for encoding a video picture sequence. The frames may consist of interlacing fields. A method for encoding interlaced video, wherein inter-prediction of fields is used and reference lists are assigned to the fields for indicating reference frames or fields, comprises that, if within such reference list a reference to another frame is included, then references to both fields of the other frame are included separately in direct sequence. Further, a temporal level is assigned to each of the frames according to their display order, and for the frames of all except one temporal level the quantization parameter is higher for one type of fields than for the other type of fields.

Abstract: The invention relates to a method for generating for at least one block of pixels of a picture of a sequence of progressive pictures at least one motion predictor and at least one texture predictor from motion data, respectively texture data, associated with the pictures of a sequence of low resolution interlaced pictures.